Protecting device for end-on-end contact tubes in circuit breakers



Oct. 29, 1957 A. LATOUR 2,811,613

PROTECTING DEVICE FOR ENDONEND CONTACT TUBES IN CIRCUIT BREAKERS Filed June 9, 1954 INVENTOR. ANDR LATOUR TM. mm

AT TORNE Y Unite PROTECTING DEVICE FOR END-ON-END CON- TACT TUBES IN CIRCUIT BREAKERS Andr Latour, Grenoble, France, assignor to Etablissements Merlin & Gerin, Grenoble, France The invention refers to a protecting device for end-onend contacts in circuit breakers and is particularly concerned with a protecting device for contacts in tube form extended symmetrically to both sides of the plane of contact of circuit breakers where one of the contacts or both are moved in the opening cycle by a pressure fluid, compressed air or gas, and in the closing cycle through the action of a spring or springs.

In circuit breakers of this type the compressed air acts only gradually upon the piston or pistons which command the separation of the contacts and start the movement of the contact or contacts only after the tension of the spring or springs has been overcome which press the contacts strongly together. The contacts thus are only slowly opened.

Conversely, however, the contacts are extremely abruptly closed under the action of the closing spring which will be operative alone, or together with and in the same sense as the pressure medium when such is to be admitted to initiate the closing cycle. The contact or the contacts, on impact, will thus rebound and arcs will transitorily be formed which will afiect the contact surfaces. The contact surfaces will thus become dull or mat.

It is therefore an object of the invention to overcome these inconveniences and it is particularly an object of the invention to provide a protecting device at the contacts of a circuit breaker of the aforesaid type which makes possible to ensure, on the one hand, a precise sharp opening of the contacts and, on the other hand, during the closing cycle of the circuit breaker, to avoid any rebounding and undesired opening of the contacts.

An object of the invention thus is to render to some extent the electrical closing and opening operations independent of the variations of the velocity and thus of the acceleration and deceleration of the masses of the contacts to be moved by the pressure medium against the tension of the spring in the one sense, and by the action of the spring in the other sense.

' In order to achieve these and other objects, the invention provides, in a circuit breaker with a pair of tubular end-on-end contact members for a pressure medium operated opening cycle and a spring operated closing cycle, the tubular contact members forming conduits for the pressure medium. One of the tubular contact members is constituted by a principal contact tube and an auxiliary contact tube of a length and a mass small relatively to those of the principal contact tube, or both contact members are so constituted. The auxiliary contact tube is carried by the principal contact tube, telescopically slidable for limited movement thereupon. Both the principal and the auxiliary contact tubes present with their end faces, directed towards the contact face of the other tubular contact member, for cooperation therewith, two contiguous annular zones of a composite contact face. An auxiliary spring is disposed between the auxiliary contact tube and the principal contact tube carrying it States Patent and is tensioned to urge the auxiliary contact towards the other one of the tubular contact members. The auxiliary contact tube with its annular contact zone projects, in the open position of the tubular contact members, from the annular contact zone of the principal contact tube. Thus, under the tension of the auxiliary spring and when during the opening cycle the tubular contact members are separating, the annular contact zone of the auxiliary tube will first hold the circuit closed and on further movement, or on continuance of the opening cycle, open the electric circuit. Conversely, during the closing cycle, under the action of the contact closing spring of the circuit breaker and against the tension of the auxiliary spring, the projecting annular zone of the auxiliary contact tube will, under the small momentum of this auxiliary contact tube, first establish the initial contact between the annular contact zone of the auxiliary contact tube and the annular contact zone of the other tubular contact member. Thereupon, on continuance of the closing motion, the auxiliary contact tube will be telescoped back into its principal contact tube and contact between the contact face of the other tubular contact member and the annular contact zone of the principal contact tube will also be established. To these purposes, the auxiliary spring is designed strong relatively to the mass or inertia of the auxiliary contact tube and sufiicient to brake but not to compensate the action of the main contact ciosing spring.

Both main contact tubes may be identically provided with auxiliary contacts and auxiliary springs. However, since the desired effect may be fully achieved when only one of the contact tubes is so provided, the manufacturing cost may be considerably reduced when the auxiliary contact device of the invention is provided only at one of the tubular contact members. The device is particularly advantageous because provision is made whereby the symmetry of the contact faces, essential for the electric conditions of the operation, is preserved in the open position as well as in the closed position of the contact tubes.

To this purpose the face of the second tubular contact member, which may or may not carry an auxiliary contact tube, is shaped with a profile which is symmetrically identic with the profile which the principal contact tube of the first tubular contact member together with its projecting auxiliary contact tube presents.

Under these conditions the projecting part also of a one-piece contact tube contributes in the telescoping back of the auxiliary contact tube into the principal contact tube of the first tubular contact member.

These and other features and objects of my invention will become apparent as the now ensuing specific description of the invention proceeds in which the invention will be described with reference to the accompanying drawings which form part of this specification and which by way of example illustrate an embodiment of my invention. These drawings are to be understood explicative of the invention but not limitative of its scope. Other embodiments incorporating the principle underlying my invention are feasible without departing from the spirit and ambit of my appended claims.

In the drawings:

Fig. 1 is an elevational section of pneumatic circuit breaker with tubular end-on-end contacts of the type to which the invention may be applied;

Fig. 2 is an elevational section on an enlarged scale of the contact making and breaking portions of the tubular contact members, such as between lines 2 of Fig. 1, one of the tubular contact members being provided with an auxiliary contact tube in accordance with the invention;

Fig. 3 is a cross section along line 33 of Fig. 2; and

Fig. 4 is a fraction of Fig. 2, showing the contact ends in closed, telescoped positions.

In the drawings, the main contact tubes are designated by 11 and 12. In Fig. 1, they are shownintheelosed po; sition. When the contacts are to be, opened, pressure fluid such as compressed air is admitted through thepres sure fluid line 13 into the space 14 of the circuit breaker, the pistons 15, 16 upon the contact tubeswill open the contact tubes overcoming the tension ofv springs 17,113. Compressed air will flow, guided through sleeve 19 in to the channels 21, 22;, within tubes 11, 1 2, respectively, and ionized air or other fluid may escape to. the outside through valves 23, 24. Since the pressure of the pressure fluid holds valves 25, 2 6 closed, through lines 27, 2 8, the contacts will remain open, until, subsequently, they are closed through any appropriatemeans. T this purpose valves 23, 25 and 24, 26, may be displaced, as a rule through remote control. Pressure medium from space 14 will be admitted to both sides of pistons 15,16, directly to the one sides and through ducts 27,28 and'now open valves 25, 26 to the other sides. The. pressure through the pressure fluid on both sides of the pistons thus is equalized, springs 17, 18 will prevail and close the contact tubes.

Fig. 1 has merely been shown for illustrating the function and operation of the contact tubes, which in so far, is well known in the art.

The invention will now be described with reference to Figs. 2 to 4. These figures illustrate an embodiment of the invention applied to one tubular contact member only. It will be readily understood that the invention may be applied to both tubular contact members where then the same arrangement will be applied at both tubular contact members, merely symmetrically reversed the one relatively to the other. Furthermore, whereas the embodiment is illustrated as applied to a circuit breaker with both tubular contact members movable, the arrangement will be the same when only one of the tubular contact members is movable. In this latter case the device of the invention may be applied to either tubular contact member, if only the conditions as to the symmetry of the contact profiles and the power relation of main spring and auxiliary spring, as above described, are satisfied.

In the contact device of Figs. 2 to 4, one of the movable tubular contact members is constituted by. a principal contact tube 11 housing, telescopically displaceable therein, an auxiliary contact tube 31. Auxiliary contact. tube 31 is urged towards the other tube contact 12 by means of a compression spring 32. Spring 32 bears with its one end against the thrust face 34 of a collar'33 upon and as illustrated integral with the auxiliary tube and with its other endagainst a ring 36 secured to principal contact tube 11 by being screwed into an inner screw thread 37 thereof. In the open position of the tubular contact members, auxiliary contact, tube 31 with the second thrust face 35 of its collar bears against the inwardly projecting rim 38 of the principal contact tube 11;

Contact tube 11 may consist of two length parts, the rear part which carries the piston 15 being screwed into screw thread 37.

In order to ensure electric continuity between contact tubes 11 and 31, a sleeve 41, enclosing spring 32, embraces collar 33. Sleeve 41 at its one end is secured to ring 36, for instance inserted in a cylindrical groove 42. At its other end, sleeve 41 is slitted, laminae 43 or prongs thus are shaped which by means of a coil spring 44 in ring-form are centripetally pressed against the collar 33 of the auxiliary contact tube 31 thus providing an effective,elastic, sliding electrical contact between main tube 11- and auxiliary tube 31, and suflicient cross sectional area of conductive copper material for the passage of currents of considerable amperage. Any formationof the conductive paths more or less in loop form is thus avoided which might cause the production of electrodynamic forces.

In further development of the invention, the projecting contact end of auxiliary contact tube 31 is shaped as an annular projection 45. In the ope-n position of the tubular contacts, Fig. 2, projection 45 protrudes, urged by the auxiliary spring 32, from the contact face 46 of tube 11. Projection 45 however is pushed back into or to the rear of; contactface 46, on contact with the contact face of the other tubular contact member 12 under the action of the auxiliary spring 32. Contact 12, likewise, is shaped integrally, with an annular projection 47; protruding from the contact face 48 and of equal shape with the annular projection 45 of the auxiliary contact tube. Thus, when the contacts are closed, projection 47 will push projection 45 of auxiliary contact tube 31 back into the cylindrical bore of tube 11, and the main contact faces or annular contact zones 46, 48 of the tubes as well as the contiguous annular contact zones of the projections 47-, 45, will be in contact with each other, Fig. 4', the tubular contact membersthus contacting each other'with two contiguous zones of annular composite contact faces;

By means of this device, during the opening cycle of the. circuit breaker, while, through the action of the pres sure medium on the pistons 15, 16, the main contact tubes 11, 12 start their opening motion, the projections 45, 47 still remain in contact, auxiliary springv 32 expand;- ing while tube 11 is withdrawn. Only when during its withdrawal rim 38 reaches the thrust face 35, will the pro? jections 45 and 47 be separated from each other and the current interrupted.

The electrical opening of the circuit thus. ensues only when the principal contacts have substantially reached or approached uniform velocity, thus is independent of the inertia of the main contact tubes andof their acceleration but depends substantially only upon the movement of the auxiliary contact tube of relatively small mass or inertia. The breaking of the current is thus sharpand at a precise instant.

Conversely, during the closing cycle, the contact be? tween projection 47 of tube 12 and projection 45' of auxiliary contact tube 31 will already have been estab:- lished and the current been closed, when the masses at their impact are to be decelerated, Any mechanicaLrebound of the main contact tubes will leave theelectrical contact between auxiliary contact tube and tubular con:

tactmember 12 undisturbed and will thus be without;any adverse effect on the continuity of the; electric contact. Spring 32 and, the friction between prongs 43 and collar. 33, will moreover execute a damping elfect on any -me chanical. oscillationsbetween main and auxiliary contact tubes.

Theelectric current will thus be opened and closedfree from any disturbances.

I claim:

1. Contact device for circuit breakers with a pair ofi tubular end-on-end contact members provided'withdriv ing means for a pressure operated opening cycle and a: spring operated closing cycle thereof and forming conduits for said pressure medium; at least one of said tubu lar contact members being constituted by a principal con tact tube and an auxiliary contact tube of a length and. mass small relatively to those of the principal contact tube and carried thereby, telescopically slidable for limited movement thereupon; both said principal contact tube and said auxiliary contact tube presenting with their, end faces, directed towards the contact-face .of the other one of said tubular contact members, for cooperationtherewith, two contiguous annular zones of a composite contact face; an auxiliary spring being disposed in the principal contact tube, said auxiliary spring being ten; sioned to urge said auxiliary contact tube towards the other one of said tubular contact members; said auxil; iary contact tube projecting with its annular contact zone from theannular contact zone of-the principal contact tube, thereby, under the tension of the auxiliary spring and when during-theopening cycle the tubular contact members are separating both contacts, in opened po sition, being symmetrical with respect to the plane along which the annular contact zones at the principal contact come in touch in closed position, first to maintain and thereon, on continuance of the opening cycle to open the electric contact, and, conversely, during the closing cycle, under the action of the contact closing spring and against the tension of the auxiliary spring, first, under the small momentum of said auxiliary contact tube, to establish the initial contact between the annular contact zone thereof and the contact face of said other tubular contact member and, thereon, on continuance of the closing motion, to telescope back said auxiliary contact tube and establish also contact between the contact face of said other tubular contact member and the annular contact zone of the principal contact tube; said auxiliary spring being designed strong relatively to the inertia of the auxiliary contact tube and sufiicient to brake but not to compensate the action of said contact closing spring.

2. Contact device for circuit breakers with a pair of tubular end-on-end contact members provided with driving means for a pressure operated opening cycle and a spring operated closing cycle thereof and forming conduits for said pressure medium; at least one of said tubular contact members being constituted by a principal contact tube and an auxiliary contact tube of a length and mass small relatively to those of the principal contact tube and housed, telescopically slidable, therein for limited movement relatively thereto; both said principal contact tube and said auxiliary contact tube presenting with their end faces, directed towards the contact face of the other one of said tubular contact members, for cooperation therewith, two contiguous annular zones of a composite contact face; an auxiliary spring being disposed in the principal contact tube housing the same, said auxiliary spring being tensioned to urge said auxiliary contact tube towards the other one of said tubular contact members; said auxiliary contact tube being shaped with a projection carrying said annular contact zone and projecting therewith from the annular contact zone of the principal contact tube thereby, under the tension of the auxiliary spring and when during the opening cycle the tubular contact members are separating both contacts, in opened position, being symmetrical with respect to the plane along which the annular contact zones of the principal contact come in touch in closed position, first to maintain and thereon, on continuance of the opening cycle to open the electric contact, and, conversely, during the closing cycle, under the action of the contact closing spring and against the tension of the auxiliary spring, first, under the small momentum of said auxiliary contact tube, to establish the initial contact between the fit annular contact zone of said projection and the contact face of said other tubular contact member and, thereon, on continuance of the closing motion, to telescope back said auxiliary contact tube with its projection into said principal contact tube and establish also contact between the contact face of said other tubular contact member and the annular contact zone of the principal contact tube; said auxiliary spring being designed strong relatively to the inertia of the auxiliary contact tube and suflicient to brake but not to compensate the action of the contact closing spring.

3. Contact device as set forth in claim 2 wherein the contact face of the other one of said tubular contact members is provided with an annular projection of equal shape with the projection of said auxiliary contact tube thus being adapted on having telescoped back the auxiliary contact tube into its housing contact tube to enter into the cylindrical bore thereof.

4. Contact device as set forth in claim 2 including a cylindrical sleeve surrounding with its one end said auxiliary contact tube, means for conduetively securing said sleeve at its other end to said housing principal contact tube, the first said end being slitted to form prongs, a circular coil spring surrounding said prongs and pressing them to bear under pressure against the circumferential surface of the auxiliary contact tube.

5. A contact device for a circuit breaker of the type having a pressure operated opening cycle and a spring operated closing cycle comprising in combination a pair of main contact members of cylindrical configuration and disposed in end to end relationship to engage in a plane normal to the respective longitudinal axes, an auxiliary cylindrical contact element coaxially supported for sliding motion Within one of the said main contact members, the other said main contact member defining two contiguous annular contacting faces with the said one main contact member and the said auxiliary element, a spring urging the said auxiliary element toward the said other main contact, a projection formed on the engaging face of the said other main contact whereby the two main contacts are symmetrical about the said plane when in disengaged position, whereby the said auxiliary element under the urging of the said spring slides within the said one main contact to initially engage against the said projection in a closing cycle and finally separate from the projection in an opening cycle.

References Cited in the file of this patent UNITED STATES PATENTS 896,210 James Aug. 18, 1908 2,678,984 Ramrath May 18, 1954 2,686,243 Latour Aug. 10, 1954 

